5 types of infections

Infectious diseases cause a major health problem worldwide, despite effective vaccines and treatments. And as a button shows: COVID-19 has shown us that pandemics are not a thing of the past With However, there are many existing infections.

Without further ado, influenza and pneumonia are the eight leading causes of death in countries like the United States, and the situation is deteriorating in lower-income countries, where respiratory infections, HIV, and diarrhea are the top three causes of death. Infections are a particularly important cause of the disease in children, the elderly and people with weakened immune systems.

This is where pathogenic microorganisms come into play , which have the ability to invade and multiply in the tissues of an organism to the point of making us sick. Every infection is different, and not all of them pose the same risk to human health, but they can be classified according to the causative agent, which can vary greatly from one to another.

What types of infections exist?

Pathogens belong to a large variety of classes, but can be roughly divided into 5 groups: bacteria, viruses, fungi, parasites and prions. Let’s get to know each other a little better and see which infections they cause are characterized.

1. Bacterial infections

They are caused by bacteria, microscopic organisms made up of a single cell that lacks a nucleus. Although there are many species that can cause disease in humans, less than 1% of existing bacteria are harmful .

• We recommend that you read: “7 most deadly bacteria in the world”

These unicellular organisms, although very simple, are self-sufficient, so they can perform all the functions necessary to survive on their own. Sometimes, there are bacteria that have structures in their membranes that allow them to attach and attach to the organs or tissues they infect, as well as attachments that allow them to move.

Bacteria that behave like pathogens can reach the human body in different ways (in the same way as harmless or beneficial ones), whether through contaminated water and food, through the air, through animals, Sexually or through direct contact with an infected person. In the same way, there are also bacteria that are very resistant to the environment, so they can come in contact with us through objects.

Once inside the body, pathogenic bacteria can reproduce rapidly and cause disease . In addition, many of them release toxins that can damage tissues. Examples of bacterial infections are salmonellosis, bacterial gastroenteritis, gonorrhea, bacterial meningitis, cavities, botulism …

Pathogenic bacterial species are so diverse and diseases that they can cause so much that it is very difficult to generalize when it comes to signs and symptoms. Many bacterial infections present with fever, if it is a gastrointestinal infection they usually cause diarrhea. They can also cause cough, nasal congestion, sore throat and cough.

Fortunately, bacterial infections can be treated with antibiotics However, the misuse of these drugs is making some bacteria resistant to most of the existing antibiotics, something that worries experts especially and that will bring us serious problems in the future.

2. Viral infections

Viral infections are caused, in excess, by viruses, which are still debating whether they should be considered living beings. Viruses are much smaller than bacteria and are so simple that they have to parasitize another cell in order to fulfill their replication functions. Hence, viruses are called obligate parasites because if they do not infect other cells they cannot to survive on their own.

There are millions of types of viruses, which have different forms as they affect different cell types, so they can cause different diseases. For example, the virus that causes COVID-19 affects the lungs and respiratory system, while the polio virus affects the nervous system and motility. Viruses that infect humans they usually have spherical shapes Although not all, and some may have a lipid envelope, such as the HIV virus and the flu virus, which helps to enter the host cell.

When a virus infects a cell, it multiplies and releases more viral agents to infect other cells and thus cause infections in the human body. Viruses can be transmitted through direct contact, through body fluids (blood, saliva, fluids) or secretions (urine, feces). People who touch infected objects or animals can also become infected.

For this reason, in the event of an epidemic, it is important to maintain good hygiene measures. However, not all viruses are equally contagious or use the same transmission routes. For example, HIV is transmitted through sexual fluids, but not through saliva. Therefore, it is vital to know well how each viral agent behaves in order to be able to take ideal precautions to protect ourselves against them.

Viruses are not treated with antibiotics As these are not effective for these infectious agents, however, there are medicines to treat some of your infections. They are called antivirals, which have the function of slowing down their development, although the immune system generally needs to neutralize and eliminate the infection.

In fact, some of the symptoms caused by viral infections, such as fever and fatigue, are sometimes the result of immune-activated defense mechanisms to fight infection. Therefore, vaccines are an excellent mechanism to prevent viral infections, as they include training for the immune system so that it “learns” to identify and attack viruses more effectively.

• We recommend that you read: “5 most deadly viruses for humans”

3. Fungal infections

Also called mycosis These infections are caused by fungi, a very diverse group of organisms, as there are unicellular and multicellular fungi. Although these are not known to be pathogenic, there are species capable of causing infections and causing disease (which are single-celled forms).

They are distinguished from bacteria in that they have a plant wall similar to that of plants, but they do not photosynthesize, but are common and nourished through the absorption of nutrients. They reproduce by flowering and producing spores. They are usually experts at infecting the superficial regions of our body, such as the skin or nails, although there are also species that colonize the genitals or digestive system.

When they manage to infect the human body, they cause diseases that are not normally serious but are very annoying and contagious . . When they colonize internal organs such as the lungs, blood or brain, they can cause potentially serious infections.

Yeast infections are treated with antifungals, which are usually quite effective. Even so, fungal infections are known to recur, which means that sometimes, even if the person is cured, the infection can recur in a short period of time. Among fungal infections we find worm, dermatophytosis and athlete’s foot.

4. Parasitic infections

There are many types of human parasites that are capable of causing us infections as parasites are organisms that must infect us in order to reproduce. A parasite is any organism that, in order to complete its life cycle, needs to infect another living being .

They are very different forms of life as there are parasites of microscopic size in multicellular organisms such as worms or earthworms. On the one hand we find protozoa, which are microscopic and unicellular and belong to the animal kingdom. They are usually transmitted through contaminated water or from the bite of a mosquito, as in the case of malaria. Protozoa are a leading cause of disease and death in developing countries.

On the other hand there are helminths, which are more complex organisms and are also considered animals. Humans get these pathogens by accidentally swallowing their eggs, which are shed in the feces of infected people.

In places where there are no proper hygienic measures and there is no water drainage, the spread of eggs is very fast With However, there are effective treatments to cure helminthiasis. In countries with more resources, cases tend to be less frequent and tend to affect children, with ascariasis being an infection par excellence in day care centers.

5. Prion infections

Prions are infectious particles of a protein nature that have the ability to cause changes in the animal body. It certainly seems more familiar to you if we talk about mad cow disease, as it is a disease caused by a prion. They are essentially proteins with infectious capacity .

Unlike the debate raised by viruses, prions are not considered living beings, but they have infectious abilities, that is, they are capable of reaching a healthy person and causing a neurodegenerative disease. People can sometimes get these infectious particles when they eat contaminated meat products.

These types of infections are very rare but extremely serious as they are not curable and almost always fatal. In fact, Creutzfeldt-Jakob disease (better known as mad cow disease) is the only disease in the world with a 100% mortality rate. Prion causes a degenerative disease that begins to develop with personality changes, insomnia and progresses to memory loss and difficulty in speaking, although it inevitably ends in death.